Question

(a)Briefly describe the structure of chloroplast in relation to its functions.
                     (b)State the chief functions of the chloroplast.

Answer 1

Hint: Chloroplasts are organelles found in plant cells and eukaryotic algae which helps for conducting photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide gas to provide food for the plant.

Complete answer:
(a) Chloroplasts are greenish plastids which possess photosynthetic pigments, chlorophylls and carotenoids and take part in the synthesis of food. Majority of the chloroplasts of the green plants are found within the mesophyll cells of the leaves. They vary in size, shape and number. Chloroplasts are double-membrane bound organelle having an outer and inner membrane. The inner membrane is relatively less permeable to substances than outer membrane and thus, has more proteins including carrier proteins. The space enclosed by the inner membrane of the chloroplast is named stroma. The stroma contains a large number of organised flattened membranous sacs called thylakoids. The thylakoids of various grana are connected by flat membranous tubules called the stroma lamellae. The membrane of the thylakoids encloses an area called a lumen. For the synthesis of carbohydrates and proteins, The stroma of the chloroplast contains enzymes. It also contains small, double-stranded circular DNA molecules and ribosomes in them.

(b) Following are the chief functions of chloroplast:
Chloroplasts are the centres of photosynthesis or formation of organic compounds from inorganic raw materials.
Chloroplasts can trap solar energy and change it into chemical energy. The chemical energy is used by all living organisms to perform their life activities.
Chloroplasts liberate oxygen which is passed into the atmosphere. This keeps the balance of oxygen constant in the atmosphere, as oxygen is being consumed in respiration and combustion.
Chloroplasts pick up carbon dioxide and use the same in photosynthesis. This keeps the percentage of this gas balanced in the atmosphere as carbon dioxide is being constantly added up to it through combustion and respiration.
They store starch either temporarily (in higher plants) or permanently (in several algae).

Additional Information:
The absorption spectra, chlorophyll absorbs light within the red (long wavelength) and therefore the blue (short wavelength) regions of the light spectrum. Greenlight isn't absorbed but reflected, making the plant appear green. Chlorophyll is found within the chloroplasts of plants.

Note: The absorption spectra, chlorophyll absorbs light within the red (long wavelength) and therefore the blue (short wavelength) regions of the light spectrum. Greenlight isn't absorbed but reflected, making the plant appear green. Chlorophyll is found within the chloroplasts of plants.